Data Retrieval with a SubQuery | Backendless Database Training Course (pt. 41)
In this video, we will be discussing fetching data with a subquery. This feature applies to cases where you have two data tables that don't have a relation between them but share some common data. For example, let's say we have a table called Product with a column called category, which contains the names of the categories that the product records in the table belong to. There is another table called Category that defines the valid categories with some additional data about those categories, such as whether a category is a premium or not. In this example, we need to come up with a query where we fetch all the products that belong to a premium category. However, since there is no relationship between these two tables, we need to use a subquery. The subquery is a full-blown where clause that runs off the Category table. Although it has a slightly different syntax, once you understand how to structure it, you can come up with any kind of subquery.
File to download and import to get the ProductCategory table -
https://www.backendless.us/databaseco...
Have questions? Post them in the comments below or get in touch at:
Support forum: https://support.backendless.com/
Slack channel: https://backendless.slack.com/
Telegram channel: https://t.me/backendless_chat
Start with Backendless for free today to follow along with this course: https://develop.backendless.com/regis...
Happy Coding!
#database #querying